CVD growth of monolayer WS2 through controlled seed formation and vapor density

Yorulmaz, Büşra; Özden, Ayberk; Şar, Hüseyin; Ay, F.; Sevik, Cem; Perkgöz, Nihan Kosku

doi:10.1016/j.mssp.2018.12.035

Cited by 36 publications

(26 citation statements)

References 35 publications

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“…The synthesis of monolayer WS 2 was achieved via AP-CVD method. [45] 50 mg of WO 3 precursor was placed in a ceramic boat at the center of the single-zone tube furnace. Double side polished sapphire substrates were placed on the ceramic boat.…”

Section: Chemical Vapor Deposited Growth Of Transition Metal Dichalcomentioning

confidence: 99%

Room‐Temperature Synthesis of 2D Janus Crystals and their Heterostructures

et al. 2020

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Janus crystals represent an exciting class of 2D materials with different atomic species on their upper and lower facets. Theories have predicted that this symmetry breaking induces an electric field and leads to a wealth of novel properties, such as large Rashba spin–orbit coupling and formation of strongly correlated electronic states. Monolayer MoSSe Janus crystals have been synthesized by two methods, via controlled sulfurization of monolayer MoSe2 and via plasma stripping followed thermal annealing of MoS2. However, the high processing temperatures prevent growth of other Janus materials and their heterostructures. Here, a room‐temperature technique for the synthesis of a variety of Janus monolayers with high structural and optical quality is reported. This process involves low‐energy reactive radical precursors, which enables selective removal and replacement of the uppermost chalcogen layer, thus transforming classical transition metal dichalcogenides into a Janus structure. The resulting materials show clear mixed character for their excitonic transitions, and more importantly, the presented room‐temperature method enables the demonstration of first vertical and lateral heterojunctions of 2D Janus TMDs. The results present significant and pioneering advances in the synthesis of new classes of 2D materials, and pave the way for the creation of heterostructures from 2D Janus layers.

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Section: Chemical Vapor Deposited Growth Of Transition Metal Dichalcomentioning

confidence: 99%

Room‐Temperature Synthesis of 2D Janus Crystals and their Heterostructures

et al. 2020

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“…We utilize WO3 (Sigma-Aldrich, 99.5%) and sulfur (Sigma-Aldrich, 99.5%) as precursors and use N2 gas as a carrier. Also, we make use of H2 for its promoting effect [29]. We change the position of the furnace at 820°C and introduce WO3 to react with sulfur.…”

Section: Methodsmentioning

confidence: 99%

“…In the literature, the Raman spectra of the monolayer WS2 have already been reported showing that calculating the difference between the first-order modes at the Brillouin zone center (E′ and A1) is a powerful tool to identify the number of layers of 2D WS2. If the difference between E′-A1 is lower than 64.5, the flakes are accepted as monolayers [29,31]. For this reason, in the study, we mainly focus on E′ and A1 modes (Figure 3b-d).…”

Section: Methodsmentioning

confidence: 99%

Temperature Dependent (83-483 K) Raman Spectroscopy Analysis of CVD Grown Ws2 Monolayers

Öper

Perkgöz

2020

Eskişehir Technical University Journal of Science and Technology a - Applied Sciences and Engineering

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For novel materials to be used in practical applications, their temperature dependent behavior and limitations need to be understood thoroughly. For example, the mobility of charge carriers, one of the important performance parameters in transistors, strongly depend on the change in the ambient temperature. Hence, characterization of potential optoelectronic materials at extreme temperatures is critical for future applications. In this study, we report on the changes of Raman scattering spectra as the temperature is changed from 83 K to 483 K for the 2D transition metal dichalcogenide materials, namely WS2 monolayers formed by chemical vapor deposition technique (CVD). Our results show that both E′ (E 1 2g) and A1(A1g) modes red shift linearly as the temperature increases. The first order thermal coefficients have been calculated with the Grüneisen model, which suggests that in-plane mode is affected more by the increased temperature than that of out of plane mode. This difference is attributed to the defects in the sample as the flakes are grown by the CVD method. We also investigated the temperature dependence of the second order, 2LA(M) (at 345.7 cm-1) which is one of the most intense peaks in the spectra.

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“…Compared to MoS 2 , WS 2 is distinguished by superior carrier mobility and a strong photoluminescent response [30]. However, tungsten reacts less readily with chalcogen atoms compared to molybdenum, so in general tungsten TMD growths tend to lag behind their molybdenum counterparts [31]. Using a modified version of their MoS 2 growth protocol, Kang et al [27] were able to achieve 10 cm diameter films of monolayer WS 2 .…”

Section: Metal Organic Chemical Vapor Deposition (Mocvd)mentioning

confidence: 99%

Large area few-layer TMD film growths and their applications

2020

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Research on 2D materials is one of the core themes of modern condensed matter physics. Prompted by the experimental isolation of graphene, much attention has been given to the unique optical, electronic, and structural properties of these materials. In the past few years, semiconducting transition metal dichalcogenides (TMDs) have attracted increasing interest due to properties such as direct band gaps and intrinsically broken inversion symmetry. Practical utilization of these properties demands large-area synthesis. While films of graphene have been by now synthesized on the order of square meters, analogous achievements are difficult for TMDs given the complexity of their growth kinetics. This article provides an overview of methods used to synthesize films of mono-and few-layer TMDs, comparing spatial and time scales for the different growth strategies. A special emphasis is placed on the unique applications enabled by such large-scale realization, in fields such as electronics and optics.

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CVD growth of monolayer WS2 through controlled seed formation and vapor density

Cited by 36 publications

References 35 publications

Room‐Temperature Synthesis of 2D Janus Crystals and their Heterostructures

Room‐Temperature Synthesis of 2D Janus Crystals and their Heterostructures

Temperature Dependent (83-483 K) Raman Spectroscopy Analysis of CVD Grown Ws2 Monolayers

Large area few-layer TMD film growths and their applications

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